Screams and cheers erupted at Cape Canaveral, Florida as the massive rocket fired its 27 engines and rumbled into the blue sky over the same NASA launchpad that served as a base for the US missions to Moon four decades ago.
"Wow, did you guys see that? That was awesome," said SpaceX commentator Lauren Lyons as applause thundered through mission control.
SpaceX commentator John Innsbrucker said it was "everything you could want in a test flight."
Loaded with Musk's red Tesla and a mannequin in a spacesuit, the monster rocket's historic test voyage has captured the world's imagination.
This image from video provided by SpaceX shows the company's spacesuit in Elon Musk's red Tesla sports car which was launched into space during the first test. Source: AAP
However, the actual status of the car -- which was to pass unshielded through a quite harsh environment in space -- was not immediately clear.
If the Roadster does survive, the car would enter an Earth-Mars orbit around the Sun, on a journey that could last a billion years, SpaceX said.
The car was also outfitted with three cameras and a high-data storage unit containing Isaac Asimov's science fiction books series, the Foundation Trilogy.
About two minutes into the flight, the two side boosters peeled away and made their way back toward Earth for an upright landing.
Both rockets landed side by side in unison on launchpads, live video images showed.
"And the Falcons have landed," Lyons said.
The third, center booster was to attempt a landing on an ocean platform. Its status was still unclear a half hour after launch.
Experts said the launch would likely catch the eye of the US space agency NASA, which may consider using the Falcon Heavy as a way to fast-track its plans to reach the Moon again for the first time since 1972.
Falcon Heavy specs
The Falcon Heavy launced from the same NASA pad that was the base for the Apollo-era Moon missions of the 1960s and 1970s.
It is "the most powerful operational rocket in the world by a factor of two," SpaceX said.
That means it can carry twice the payload of United Launch Alliance's Delta IV Heavy, at a far lower cost -- about $90 million per launch compared to $350 million for its competitor.
But the Falcon Heavy is not the most powerful rocket ever -- just the biggest in operation today.
The Saturn V rocket that propelled astronauts to the Moon could deliver more payload to orbit. The Soviet-era Energia, which flew twice in 1987 and 1988, was also more powerful.
The Falcon Heavy is essentially three smaller, Falcon 9 rockets strapped together, adding up to a total of 27 engines.
The 230-foot (70-meter) tall rocket is designed to carry nearly 141,000 pounds (64 metric tonnes) into orbit -- more than the mass of a fully loaded 737 jetliner.
It was initially designed to restore the possibility of sending humans to the Moon or Mars, but those plans have shifted and now the Falcon Heavy is being considered mainly as a potential equipment carrier to these deep space destinations, Musk said Monday.
Instead, another rocket and spaceship combination being developed by SpaceX, nicknamed BFR - alternately known as "Big Fucking Rocket," or "Big Falcon Rocket" - would be the vehicle eventually certified for travellers.
